This invention relates in general to magnetic tape recording/reproducing apparatus and more particularly to a helical scan magnetic tape recorder/player.
Various techniques have been proposed for use in magnetic tape recorder/players for threading magnetic tape from a cassette into a tape transport path and for guiding the tape along such path. Both manual and automatic mechanical arrangements have been proposed for threading magnetic tape from a cassette. Such mechanical arrangements involve mechanical guide elements and linkages which extract a length of magnetic tape from a cassette and which move the tape to a final tape transport path. The path is defined by the guide elements and includes one or more magnetic heads. The mechanical arrangement must then provide for guiding the tape during transport past the magnetic head. Both the tape threading operation and the tape transport operation typically requires some components of the overall mechanism to be employed in one operation but not in the other operation. For example, one or more motors and associated linkages may be used for a tape threading operation but play no part in the tape transport operation. During threading operation, the various linkages and guide elements are moved over considerable distances and must be accurately located to establish a tape guide path which permits accurate recording and playback of information on the magnetic tape. Purely mechanical tape threading mechanisms are both expensive and complex and tape threading and unthreading is relatively time consuming. The following patents are illustrative of mechanical tape threading and guiding arrangements: U.S. Pat. No. 3,674,942, issued Jul. 4, 1972, Inventors--Sugaya et al.; U.S. Pat. No. 4,259,700, issued Mar. 31, 1981, Inventors--Galue et al.; U.S. Pat. No. 4,642,706, issued Feb. 10, 1987, Inventors--Vollmann et al; U.S. Pat. No. 4,541,024, issued Sep. 10, 1985, Inventor--Sieven; and U.S. Pat. No. 3,678,217, issued Jul. 18, 1972, Inventor--Kihara.
In order to ameliorate the problems associated with mechanical threading arrangements for magnetic tape recorders, various techniques have been proposed for pneumatically threading magnetic tape into a magnetic tape recorder from a cassette or cartridge. Thus, U.S. Pat. No. 4,620,678, issued Nov. 4, 1986, Inventors--Kumakura et al. discloses a cartridge loading system wherein magnetic tape contained in a single reel cartridge is threaded into a transport mechanism having a take-up reel. Threading is effected by means of air streams which carry a leading end portion of the magnetic tape from an open supply reel via a channel to a take-up reel until the leading end portion is wound around the take-up reel hub. U.S. Pat. No. 4,413,293 issued Nov. 1, 1983, Inventor--Hathaway; U.S. Pat. No. 3,940,791, issued Feb. 24, 1976, Inventors--Kayan et al. and IBM Technical Disclosure Bulletin, Volume 12, Number 6, pp. 808 and 809, dated Nov. 19, 1969, disclose arrangements for automatically threading tape contained in a two-reel cassette into a magnetic tape transport containing a helical scan magnetic head assembly or the like. The pneumatic threading arrangements disclosed in the former two patents are disadvantageous because the individually movable guide elements disclosed in these references are complex and subject to reliability problems.
Besides effecting threading of magnetic tape into magnetic tape recorder transport path, various arrangements have been proposed for using vacuum columns and the like to effect control of magnetic tape as it is transported along a path from one reel to another. Such vacuum column arrangements are disclosed, for example, in U.S. Pat. No. 3,134,527, issued May 26, 1964, Inventor--Willis; U.S. Pat. No. 3,134,528, issued May 26, 1964, Inventor--Vickey; U.S. Pat. No. 2,952,010, Sep. 6, 1960, Inventors--Vemer et al. A combined pneumatic threading and guiding arrangement is disclosed in commonly assigned U.S. Pat. No. 4,779,150, issued Oct. 18, 1988, Inventor--Grant; U.S. Pat. No. 4,772,969, issued Sep. 10, 1988, Inventor--Grant; and U.S. Pat. No. 4,763,210, issued Aug. 9, 1988, Inventor--Grant. The arrangements disclosed in the latter three patents require the application of a vacuum during both the threading and tape transport operations.
There is thus a need for a helical scan magnetic tape recorder which is reliable and cost effective, which has a minimum of components and in which tape threading and guiding is simple and reliable and in which tape threading is effected in a fast and gentle manner while minimizing stress or edge damage to the tape.